#define _CRT_SECURE_NO_WARNINGS 1
#include <stdio.h>

double Func(unsigned int n, double x)
{
	if (n == 0)
	{
		return 1;
	}
	else if (n == 1)
	{
		return x;
	}
	else
		return ((2 * n - 1) * x - Func(n - 1, x) - (n - 1) * Func(n - 2, x)) / n;
}


int main()
{
	unsigned int n = 0;
	double x = 0;
	scanf("%u%lf", &n, &x);
	printf("%.2f", Func(n, x));

	return 0;
}